On the 25th anniversary of the World Wide Web, we’re pleased to share this guest post from Sir Tim Berners-Lee, the inventor of the web. In this post he reflects on the past, present and future of the web—and encourages the rest of us to fight to keep it free and open. -Ed.

Today is the web’s 25th birthday. On March 12, 1989, I distributed a proposal to improve information flows: “a ‘web’ of notes with links between them.”

Though CERN, as a physics lab, couldn’t justify such a general software project, my boss Mike Sendall allowed me to work on it on the side. In 1990, I wrote the first browser and editor. In 1993, after much urging, CERN declared that WWW technology would be available to all, without paying royalties, forever.

How has this happened? By design, the underlying Internet and the WWW are non-hierarchical, decentralized and radically open. The web can be made to work with any type of information, on any device, with any software, in any language. You can link to any piece of information. You don’t need to ask for permission. What you create is limited only by your imagination.

So today is a day to celebrate. But it’s also an occasion to think, discuss—and do. Key decisions on the governance and future of the Internet are looming, and it’s vital for all of us to speak up for the web’s future. How can we ensure that the other 60 percent around the world who are not connected get online fast? How can we make sure that the web supports all languages and cultures, not just the dominant ones? How do we build consensus around open standards to link the coming Internet of Things? Will we allow others to package and restrict our online experience, or will we protect the magic of the open web and the power it gives us to say, discover, and create anything? How can we build systems of checks and balances to hold the groups that can spy on the net accountable to the public? These are some of my questions—what are yours?

On the 25th birthday of the web, I ask you to join in—to help us imagine and build the future standards for the web, and to press for every country to develop a digital bill of rights to advance a free and open web for everyone. Learn more at webat25.org and speak up for the sort of web we really want with #web25.